Lead monitoring in Mount Isa

Xstrata's Mount Isa operations have a number of sources of emissions to air, including the lead smelter stack, copper smelter stack, and fugitive emissions from mining, ore transport, ore preparation, sintering and smelting operations, and waste disposal. The acid plant and various industrial activities are also sources of emissions to the air in Mount Isa.

Currently, the ambient air quality limit for lead from the smelters are set in the Mount Isa Mines Limited Agreement Act 1985 (MIM Act), and mirrored in the environmental authorities. The limit for lead requires that the company shall not cause the quarterly running average concentration of lead to exceed 1.5 µg/m³ (as PM₁₀—particulate matter 10 µm or less in size) at any of five monitoring stations located at sites specified in the MIM Act.

The relevant legislation covering the Mount Isa operations was amended in May 2008 to provide for the operations to transition to contemporary environmental standards and goals, including those set in the Environmental Protection (Air) Policy 2008 (EPP (Air) 2008).

The monitoring stations, shown in the map below are located at:

• Kruttschnitt Oval
• BSD
• RSL
• Miles Street
• Racecourse.

Xstrata undertakes particulate monitoring at the five sites for PM 10 and Total Suspended Particulates (TSP) over a 24-hour period on a six-day cycle. Particulate samples are analysed for lead, cadmium, arsenic and mercury. The lead analysis is performed at the Queensland Government Safety in Mines Testing and Research Station.

Monitoring data from these stations is provided by Xstrata to the Department of Environment and Heritage Protection on a monthly basis. The analysis results are shown graphically as:

• PM₁₀ lead against the MIM Act requirements
• TSP lead against the National Environmental Protection (Ambient Air Quality) Measure (Air NEPM) standard/EPP (Air) 2008 goal.

Data graphs are available.

It is important to note that the EPP Air goal and the Air NEPM standard for TSP lead are not statutory requirements for Xstrata's operations.